Actually, Asus seems to think the motherboard will work with 1GB DIMMs for a max 2GB
Actually I would take what ASUS say with a pinch of salt!
I have an older ASUS mobo that says on their website and in the manual that it can take 2GB max (1GB in each of two slots). Well it doesn't, and ASUS finally admitted the fact in a reply on one of their forums (where a lot of pissed-off punters - like me - had wasted cash and time trying to get 2GB to work).
SD